Bump external/ubpf from caa0081 to 6628f4a (#4148)

Bumps [external/ubpf](https://github.com/iovisor/ubpf) from `caa0081` to `6628f4a`.
- [Commits](iovisor/ubpf@caa0081...6628f4a)

---
updated-dependencies:
- dependency-name: external/ubpf
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>